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New Method for Ship Detection
Jian Yang Hongji ZhangDept. of Electronic Eng., Tsinghua Univ.
Yoshio YamaguchiDept. of Inform. Eng., Niigata Univ.
Outline
Background Polarization Entropy and Similarity Parameter GOPCE based ship detection Experiment Results Summary
1. Background
Polarimetric Whitening Filter (PWF) Novak, Burl
Identity Likelihood Ratio Test DeGraff
HH HV VV RR LL Entropy Span Touzi
Touzi’s work
Optimization of Polarimetric Contrast Enhancement (OPCE)
maxt
At
B
K
K
h g
h g
Ioannidis Hammers Kostinski Boerner Yamaguchi Yang
2 2 21 2 3 1h h h
2 2 21 2 3: 1subject to g g g
Problem
Can we employ the OPCE for ship detection?
It is easy to get the average Kennaugh matrix of sea clutter, but how can we get or construct the average Kennaugh matrix of ships?
Can we extend the OPCE for ship detection?
2 Polarization entropy and similarity parameters
11 12 13 1* H
12 22 23 2* *
13 23 33 3
H H H1 1 1 2 2 2 3 3 3
T T T
T T T
T T T
T U U
U U U U U U
3
31
logi ii
H P P
3
1i i j
j
P
Approximate expressionApproximate expression
11 2 0.006H AH dk dk
From the least square method and Vieta's Theorem2
2 3 43.9408 7.5818 5.3008
b c bAH
a a a
11 22 33
11 22 11 33 22 33 12 12 13 13 23 23
a Span T T T
b T T T T T T T T T T T T
c
T
The average error:
The Formula has a good approximation to the The Formula has a good approximation to the theoretical value of the polarization entropytheoretical value of the polarization entropy
Eigenvalues and logarithm are unnecessary!!!
Running Time by the proposed formula is only 5% of that by the traditional approach
J. Yang, Y. Chen, Y. Peng, Y. Yamaguchi, H. Yamada, “New formula of the polarization entropy”, IEICE Trans.
Commun., 2006, E89-B(3), 1033-1035
1, ,2
2
T
hh vv hh vv hvk s s s s s Similarity parameterSimilarity parameter
20 H 01 2
1 2 2 20 01 22 2
( )( , )r
k kk k
k k
single-look case
Multi-look case
H0 00 01 21 2
1 20 0 H H0 0 0 0
1 2F F 1 1 2 2
tr,( , )
tr trR
T TT TT T
T T T T T T
J. Yang, et al., “Similarity between two scattering matrices,” Electronics Letters, vol.37, no. 3, pp. 193-194, 2001.
2 2 20 0 0HH VV HV
20 0HH VV
1
2 20 0HH VV HH VV
1
, 020
2
2 2
S
S S S
S S
Sr r
S S
Span Span
k
Similarity between a target and a plate:surface scattering
Similarity between a target and a diplane:Double-bounce scattering
20 0HH VV
2
0
, 1
02
S Sr r
Span
k
Generalized OPCE (GOPCE) based ship detection
J. Yang, Y. Yamaguchi, W. -M. Boerner, S. M. Lin, “Numerical methods for solving the optimal problem of contrast enhancement,” IEEE Trans. Geosci.
Remote Sensing, 2000, 38(2), pp. 965-971
maxt
At
B
K
K
h g
h g
2 2 21 2 3 1h h h
2 2 21 2 3: 1subject to g g g
20 0
1 2 2 20 0 0([ ], (1,1))
2( 2 )
HH VV
HH VV HV
s sr r S diag
s s s
20 0
2 2 2 20 0 0([ ], (1, 1))
2( 2 )
HH VV
HH VV HV
s sr r S diag
s s s
3 :r Cloude entropy
GOPCEGOPCE: : GGeneralized eneralized OPCEOPCE
23
1
ti i m m
i
GP x r K
h g
23
123
1
max
ti i m A m
i
ti i m B m
i
x r K
x r K
h g
h g
J. Yang, et al., “Generalized optimization of polarimetric contrast J. Yang, et al., “Generalized optimization of polarimetric contrast enhancement”, IEEE GRSL., vol.1, no.3, pp.171-174, 2004enhancement”, IEEE GRSL., vol.1, no.3, pp.171-174, 2004
GOPCE based ship detection
23
1
ti i m m
i
GP x r K
h g
23
1
min ( )ti i m m
i
Var x r K
h g
For a sea areaFor a sea area
subject to: subject to: 123
22
21 xxx
Average Kennaugh matrix of ships
the scattering contributions of a ship direct reflection of plates double reflections of diplates of the
ship some multi-reflections of the
surface of the ship, or some multi-reflections between the ship and the sea surface ( ) (0) ( )
plate diplate diplate multiK TA a K b K c K d K
0: 0.4, 0.5, 0.1, 0, 45For example a b c d
Experimental results
NASA/JPL AirSAR over Sydney coast, Australia.
Span image
Experiment results
(1, 0.9453, -0.1497, 0.2897)tm g
( ) (0) ( )plate diplate diplate multi
K TA a K b K c K d K
00.4, 0.5, 0.1, 0, 45a b c d
23
1
ti i m m
i
GP x r K
h g
(1, -0.6313, 0.2925, 0.7182)tm h
(-0.4000, -0.2750, 0.8743)tm x
Experiment results
Power Image by OPCE
Experiment results
GP Image by GOPCE
Experiment results
Filtered result by PWF
span PWF
OPCE GOPCE
Detection results: false alarm rate 1%
5. Summary
(1) OPCE has been developed
(2) GOPCE is effective for ship detection
Speckle Filtering Speckle phenomenon in SAR/POLSAR
Scattering from distributed scatterers
Coherent interferences of waves scattered from many randomly distributed scatterers in
the resolution cell
Granular Noise
Speckle Phenomenon
Observation Point
Surface Roughness
24/28
Speckle Filtering Challenge of speckle filtering
Detail PreservationSpeckle Reduction
Speckle Filtering
These two objectives
should be achieved
simultaneously
These two objectives
should be achieved
simultaneously 25/28
Pre-test Approach for Speckle Filtering
Classical Methods for Speckle Filtering Boxcar Filter
MMSE Lee’s filter with edge detector
3*3 boxcarTo-be-filtered pixel
Pixel selected for averaging
8-direction edge detectors
26/28
Pre-test Approach for Speckle Filtering
Selecting homogenous pixels Averaging homogenous pixels
Boxcar localarea
In neighboring area Uniformly weight
Lee In aligned matching window By mmse criteria
Pre-test In non-local area By the similarity of patch
To-be-filteredpixel
Pre-tested pixels
Summary of Speckle Filtering : Two-Step MethodologySummary of Speckle Filtering : Two-Step Methodology
An example of pre-testing homogenous pixels in non-local
area by patch
patch
patch : pixel itself and itslocal neighboring
non-local area : other than neighboring area
pre-test : selecting homogenouspixels in non-local area by patch
27/28
Pre-test Approach for Speckle Filtering Non-local but homogeneous pixels using proposed
method
28/28
Pre-test Approach for Speckle Filtering
For each pixel - For each pixel in non-local searching area
1. Calculate the similarity test between the patches with and
as the center respectivel2. If test > threshold, accept as the homogenous pixel to
, and calculate the weight3. Average homogenous pixels with their normalized weight to get filtered covariance matrix
,i jT
,i ix y
,j jx y
searching area of ,i ix y
,i ix y
,j jx y
,i ix y,j jx y
,i ix y
,j jx y
Calculate the
similarity between 2
patches
patch
,i jT
29/28
Pre-test Approach for Speckle Filtering
Experimental Results
(a)Original (b) Refined Lee (c) Pre-test
SAR-Convair 580 C-bandImage size : 340*220
Resolution : 6.4m*10m
30/28
C-band AirSAR data
SAN Francisco area (a)Original(b)Boxcar
(c)Refined Lee(d)Pre-test
4 multi-look Image size :
300*300Resolution :
About 10m*10m
31/28
